The commercial wireless industry continues to drive for size, weight, and cost reduction of wireless devices, while at the same time driving the performance enhancement of these devices. Significant progress has been made in the integration and size reduction of frequency processing functions in semiconductor products, but the integration of frequency selective devices that require many passive components has lagged. Efforts are underway to integrate passive components into organic printed circuit boards, but frequency selective devices, such as VCOs and filters, require higher quality (Q) components than the typical PCBs can deliver.
Multilayer Ceramic Integrated Circuits (MCIC), utilizing a low temperature co-fired materials system, has proven that high Q passive components can be integrated in this technology to form individual devices such as transmit/receive (T/R) switches and filters.
While MCIC has made a dent in the size and weight reduction of wireless devices, its significant impact occurs when multiple functions are combined into the integrated circuit. Recently, the integration of a major portion of a wireless radio's receiver front-end into a single MCIC unit has been demonstrated.
FIG. 1 shows a block diagram of the major components of a typical radio transmit/receive front-end. These front-end components include filters, mixers, voltage controlled oscillators (VCOs), amplifiers, a switch or duplexer and an antenna. In addition to these major components, there are a myriad of smaller components, such as resistors, capacitors, and inductors, as well as transmission lines that provide support functions. These support functions include biasing, coupling, and blocking. In accordance with the prior art design techniques, these various components are oftentimes discretely placed on the radio printed circuit board.
The placement of transmission lines between stacked sheets of dielectric has been known to designers in the relevant art. For example, Gu et al. taught of a Transmission line device Using Stacked Conductive Layers in U.S. Pat. No. 5,499,009 (issued Mar. 12, 1996), and Kommrusch et al. taught of a Commonly Coupled High Frequency Transmitting/Receiving Switching Module in U.S. Pat. No. 5,584,053 (issued Dec. 10, 1996). Similarly, R. F Huang and R. Kommrusch presented "The Development of a Multilayer Ceramic Antenna Switch for Wireless Communications" at the Proceedings of the Symposium on Materials and Processes for Wireless Communications, Boston, Mass. (Nov. 15-17, 1994). These patents and this paper, to the extent necessary are incorporated herein by reference.
Referring to FIG. 1 in detail, the typical components of a radio's RF front end are provided in block diagram 100. A signal is received through an antenna 102 and first encounters a lowpass filter 104. Next, the signal encounters a transmit/receive switch 106 which may be in a first or a second position. One possible path for the signal involves passing through an oscillator 114, a mixer 112, a power amplifier 110 and then a power driver 108. An alternative path for the signal involves passing through a bandpass filter 116, a low noise amplifier (LNA) 118, a bandpass filter 120, an amplifier 122, a bandpass filter 124, a mixer 126 and an oscillator 128. In either event, it is evident that various components and functions are needed to properly control the signal in a radio RF front end.
A ceramic multilayer package module which incorporates a Transmit/Receive (T/R) switch with a harmonic filter, two band reject filters, one bandpass filter, an impedance matching network, bias circuitry, and a low noise amplifier and which is small in size in the order of approximately 500 mils by approximately 500 mils by approximately 90 mils and which contained approximately 44 embedded passive components and contained approximately 11 components mounted on its top surface and which doubled component density over previous designs, would be considered an improvement in the art.